The doctors at Pediatric Health Associates recognize the importance of healthy hearing and believe that detection of hearing loss is a fundamental aspect of every patients’ care. We are so excited to have our Otoacoustic emissions machine, a state of the art hearing test that allows us to test hearing in children of all ages and mental capacities. Gone are the days when our patients have to be old enough to wear headphones, sit still, and raise their hands to subtle tones.
Hearing loss in children is a significant problem that is more common than most people realize. Almost 75,000 children receive special educational services for hearing impairment each year in the United States. About 1/1000 children have profound hearing loss. And even more children, many unrecognized, have less severe deficits. Early detection of hearing loss is imperative because the critical period for learning language is the first 36 months of life. Screening at birth and careful attention to speech and language development should be able to detect hearing deficits while children are young.
Additionally, we stress that parents work hard to protect the hearing that their children have. With almost all kids plugged into their I-pods, noise induced hearing loss has become a significant problem. Parents of children diagnosed with hearing loss often do not know where to go for help nor are they aware of available therapies. New technologies, including advanced hearing aids, FM devices, and even cochlear implants, afford greater opportunities for the hearing impaired.
Hearing is complex. This sense requires the proper functioning of the ear and the ability to understand speech. The sound waves enter the outer ear through the pinna and auditory canal. The tympanic membrane transmits the vibration through the middle ear bones to the hearing organ in the inner ear, the cochlea. The neurological signals are then sent to the auditory nerve and then to the brain, allowing hearing. Hearing loss can result from a problem in any of these steps
Hearing loss can be described or classified many different ways. For instance, congenital vs. acquired, genetic vs. non-genetic, conductive vs. neurosensory, and unilateral vs. bilateral are common ways of differentiating the types of hearing losses. Three in 1000 babies are born with some degree of hearing loss. Approx 1/3 are due to identifiable genetic causes, 1/3 from identifiable non-genetic causes, and 1/3 result from causes that cannot be identified (in this last group probably half are genetic and half are not). Conductive hearing loss results from a problem in the outer or middle ear. It is most commonly due to fluid or wax, and is usually temporary. Neurosensory hearing loss (NSHL) results from a problem in the inner ear and can be permanent.
Severity of hearing loss is usually described in terms of the minimum intensity of sound a person can hear. Sound is measured in decibels (dB). The American Academy of Otolaryngology uses the following classification: Mild=15-40dB, Moderate=40-60dB, Severe=60-90dB, Profound=over 90dB. Examples of sound at each intensity can put these numbers into perspective. The threshold of normal human hearing is essentially zero dB, which is the sound of a mosquito flying 10 ft away. A whispered voice is 30dB, a quite restaurant 40 dB, normal conversation 60dB, and a power mower 90dB.
Genetic causes of hearing loss have to do with the baby’s genes. More than 400 types of genetic causes of hearing loss have been identified. While some of these causes are associated with specific genetic syndromes, most are not. Approximately 50% of childhood non-syndromic hearing loss is caused by mutations in the Connexin 26 (Cx26) gene, making it the most common form of autosomal recessive nonsyndromic hearing loss. Surprisingly, as many as 1 in 36 (2.8%) people carry this gene.
Non-genetic hearing loss is most often caused by trauma or illness. Children can be born with hearing loss resulting from an infection during pregnancy or they may acquire a hearing loss due to trauma or illness during childhood.
One of the most common types of acquired hearing loss is noise-induced hearing loss (NIHL). Children are exposed to noise in the environment every day. When sounds are too loud or loud sounds are present over a long time, sensitive structures in the inner ear can be damaged. The damage can be cumulative and permanent. Most people are unaware that this is even taking place and do very little to prevent NIHL in their children.
Impulse sounds can lead to serious damage to the inner ear and immediate hearing loss (i.e. firecracker=150dB). This damage may result in ringing or buzzing in the ear. Continuous exposure to loud noises (over 80dB) may result in NIHL, but the symptoms may increase gradually over time. Individuals may be unaware of early hearing losses, but over time sounds become muffled and distorted.
NIHL is especially concerning for children because of the increase in the use of headphones with I pods and other digital music players. A study conducted by the Center for Disease Control and Prevention demonstrated that 1 in 8 children have NIHL present in 1 or both ears. 15.5% of children ages12-19 years had NIHL. That is 1 in six teenagers have detectable hearing loss due to loud noises.
NIHL is preventable. Simply understanding which noises can cause damage to the ear, wearing earplugs or other protective devices, being alert to hazardous noises in the environment can almost completely avoid this serious problem
The first step in any child with suspected hearing loss or with a speech and language delay should be a hearing test. Many tests are available. The age and developmental stage of a child often determines which test is best. Universal newborn screening has been recommended since 2000. This is achieved using a test for otoacoustic emissions (OAE). The cochlea, when healthy, will actually emit sounds when stimulated. A computer is able to analyze these sounds and determine if the cochlea is working appropriately or not.
The Auditory Brainstem Response (ABR) is a test that measures the brain’s response to sound using electrodes placed on the head. Both the OAE and ABR test do not require the active participation a child.
For older children, behavioral evaluations can be used. These tests are conducted in a soundproof booth and evaluate children’s responses to sound. Different techniques including using reinforcement with lights and playing games can provide very good evaluations of a child’s ability to hear. By 4 years old, most children can be evaluated with the same tests used for adults.
Many checklists are available to help parents determine if a child should be tested. Children demonstrate speech and language skills at predictable ages. If the following are not achieved, it could indicate that a hearing problem exists:
Birth to 3 months: Reacting to sounds, soothed by a parent’s voice, awakes by or blinks to loud noises, smiles when spoken to.
3-6 months: Quiets to parent’s voice, looks for new sounds, coos (ooh and aah), scared by loud voices.
6-10 months: babbles, enjoys musical toys, has inflections when cooing.
10-15 months: Points to objects, few simple words, follows simple requests.
18-24 months Knows body parts, 20-word vocabulary, by 24 months 50% of vocabulary is intelligible to strangers.
24-36 months: 80 word vocabulary, understands verbs, speech is 80% intelligible to strangers.
When a child is suspected or found to have hearing loss it can be overwhelming for the family. Parents often have no idea what to do or where to go. It is imperative to maximize the hearing and provide every opportunity for all aspects of development. A team approach allows for the most comprehensive and effective treatment plan. The people involved usually include an Audiologist, Otolaryngologist (an Ear, Nose and Throat doctor), Speech and Language therapist, and a Pediatrician. This range of professionals will allow for all aspects of treatment to be addressed. This includes services from diagnosis, treatment, possible prevention of further loss, and augmentation of existing hearing if needed.
When a child is diagnosed with a hearing loss, hearing aids are the main treatment to augment the ability to hear. When it comes to hearing aids most parents probably recall a grandparent with a large tan plastic hearing aid that whistled during conversations. If you knew someone with a hearing aid you probably saw it malfunction as much of the time as it was working. Hearing aids today could not be further from this picture.
Hearing aids are so small that they can be worn inside the ear canal. Technology has advanced to the point where almost all hearing aids are digital. Many are programmable and the more expensive ones offer multiple bands to match specific hearing losses at different pitches. Digital technology actually allows the aid to discriminate between speech and background noises.
Hearing aids can be worn in the canal, molded to fit in the outer ear, or worn behind the ear. For children, the best choices are still hearing aids that are worn behind the ear and connected to soft plastic molds for the canal. This style has several advantages. Most importantly, it is safer. The in-the-ear aids are made of hard plastic that is able to resist damage from wax and ear drainage. The hard plastic can cause serious damage to the skin of the ear if the child falls on that area. Also, a good aid can last 10-13 years with only the mold being changed as the child grows. A factor that is important for school age children is a Frequency Modulated (FM) systems can be hooked into the behind-the-ear hearing aids.
FM systems work like a small radio transmitter and radio receiver. The microphone is worn by a teacher and usually placed at chest level (about 6 inches away from the mouth), or at the level of the mouth (3 inches from the mouth). The microphone is connected to the FM transmitter and the child’s hearing aid picks up the signal. FM systems avoid the problems of background noises in settings like a classroom.
Cochlear Implants are a newer technology and are devices that provide sound for people who receive little or no benefit from hearing aids. Some people have such profound hearing loss or damage to the cochlea that they may not benefit from hearing aids. The cochlear implant is an electrode that is placed directly into the cochlea. It converts sounds into electrical signals that stimulate the auditory (hearing) nerve. The amount of benefit seen depends upon the age of a child at the time of implantation, the cause of the hearing loss, and family support and involvement. Improvements occur over a period of months or even years. The decision to proceed with a cochlear implant is complex and not always clear. This must be made with specialists who specifically deal with this treatment.
The goal for a child with hearing loss is to maximize their ability to hear and function. Hearing loss is a problem that needs the involvement of the family and a team of professionals. It is something that is dealt with on a daily basis with progress achieved sometimes with great difficulty over long periods. Early recognition and treatment should be the highest priority when dealing with a child’s hearing. Testing of all newborns, tracking speech and language development in every child, and evaluating suspected problems all are needed for early diagnosis. And every effort should be made to preserve and protect normal hearing in children who are fortunate to be born without the challenging problem of a hearing loss.
American Academy of Audiology (AAA) 11730 Plaza America Drive, Suite 300 Reston, VA 20190 Voice: (703) 790-8466 Toll-free Voice: (800) 222-2336 TTY: (703) 790-8466 Fax: (703) 790-8631 E-mail: firstname.lastname@example.org Internet: www.audiology.org
American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) One Prince Street Alexandria, VA 22314-3357 Voice: (703) 836-4444 TTY: (703) 519-1585 Fax: (703) 683-5100 E-mail: email@example.com Internet: www.entnet.org
American Auditory Society (AAS) 352 Sundial Ridge Circle Dammeron Valley, UT 84783-5196 Voice: (435) 574-0062 Fax: (435) 574-0063 E-mail: firstname.lastname@example.org E-mail: email@example.com Internet: www.amauditorysoc.org
American Hearing Research Foundation (AHRF) 8 South Michigan Avenue, Suite 814 Chicago, IL 60603-4539 Voice: (312) 726-9670 Fax: (312) 726-9695 E-mail: firstname.lastname@example.org E-mail: email@example.com Internet: www.american-hearing.org
American Speech-Language-Hearing Association (ASHA) 10801 Rockville Pike Rockville, MD 20852 Voice: (301) 897-5700 Toll-free Voice: (800) 638-8255 TTY: (301) 897-0157 Fax: (301) 571-0457 E-mail: firstname.lastname@example.org Internet: www.asha.org
American Tinnitus Association (ATA) P.O. Box 5 Portland, OR 97207-0005 Voice: (503) 248-9985 Toll-free Voice: (800) 634-8978 Fax: (503) 248-0024 E-mail: email@example.com Internet: www.ata.org
Hearing Loss Association of America (formerly Self Help for Hard of Hearing People, Inc.) 7910 Woodmont Avenue, Suite 1200 Bethesda, MD 20814 Voice: (301) 657-2248 TTY: (301) 657-2249 Fax: (301) 913-9413 E-mail: firstname.lastname@example.org Internet: www.hearingloss.org
National Hearing Conservation Association (NHCA) 7995 East Prentice Avenue, Suite 100 Greenwood Village, CO 80111 Voice: (303) 224-9022 Fax: (303) 770-1614 E-mail: email@example.com Internet: www.hearingconservation.org